On Forward J/ψProduction at Fermilab Tevatron

1 Pages·0.12 MB·English

by  O. J. P. Eboli

MADPH-99-1097
University of Wisconsin - Madison hep-ph/9901387
January 1999
On Forward J/ψ Production at Fermilab Tevatron
O. J. P. E´boli1,2, E. M. Gregores1, and F. Halzen1
1Department of Physics, University of Wisconsin, Madison, WI 53706, USA
2Instituto de F´ısica Te´orica, Universidade Estadual Paulista, Rua Pamplona 145, S˜ao Paulo, SP 01405-900, Brazil
TheDØ Collaboration has recentlyreported themeasurement of J/ψ production at low angle. We
show here that the inclusion of color octet contributions in any framework is able to reproduce
this data.
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CDF (Phys. Rev. Lett. 79, 572 (1997))
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DØ (Phys. Lett. B370, 239 (1996))
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DØ (FERMILAB-Pub-98/237-E)
7 DØ (FERMILAB-Pub-98/237-E)
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FIG.2. The pseudorapidity dependence of the differential
9 FIG.1. The pT dependenceof the differential cross section cross section
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p
- The DØ collaboration has recently reported the first ACKNOWLEDGMENTS
p measurementofJ/ψproductionintheforwardpseudora-
This research was supported in part by the Uni-
e
pidityregion2.5 η 3.7inpp¯collisionsat√s=1800
h ≤| |≤ versity of Wisconsin Research Committee with funds
GeV [1]. It was shown that the dependence of the J/ψ
: granted by the Wisconsin Alumni Research Foundation,
v cross section with its transverse momentum confirmed
bytheU.S.DepartmentofEnergyundergrantDE-FG02-
i
X theoretical expectations based on NRQCD [2]. Here we 95ER40896, by Fundac¸a˜o de Amparo `a Pesquisa do Es-
show that the soft color model [3] is also able to explain
r tadodeSa˜oPaulo(FAPESP),andbyConselhoNacional
a these results. The implication of this result is that this
de Desenvolvimento Cient´ıfico e Tecnol´ogico (CNPq).
data,oncemore,requirestheinclusionofcoloroctetper-
turbative diagrams for the production of ψ’s. How this
is implemented is not decisive [3,4].
Wehaveevaluatedψproductionfollowingreference[3].
Like the measurement, we included prompt production,
as well as production via b-decay. We only adjusted the
renormalization and factorization scales as appropriate [1] B.Abbottetal.(DØCollaboration), Phys.Rev.Lett.82,
for a leading order calculation. The predictions of the 35 (1999).
soft color model for the forward J/ψ production at the [2] G.T.Bodwin,E.Braaten,andG.Lepage,Phys.Rev.D51,
Tevatron is compared with the experimental results in 1125 (1995).
Fig. 1. As can be seen, the leading order evaluation of [3] J.Amundson,O.E´boli,E.Gregores,andF.Halzen,Phys.
thesoftcolormodeladequatelydescribestheshapeofthe Lett. B372, 127 (1996); Phys.Lett. B390, 323 (1997).
forward p distribution and its absolute normalization. [4] E. Braaten, S. Fleming, and T.C. Yuan, Ann. Rev. Nucl.
T
It is interesting to verify that the soft color model de- Part. Sci. 46, 197 (1996); P. Hoyer and S. Peigne, Phys.
scribes the rapidity distribution for different cuts on p . Rev.D57, 1864 (1998).
T
The result is shown in Fig. 2, and a good agreement is
obtained.
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